text:
What is the regulatory landing distance for turboprops under FAR 121-135?
Flying a FAR part 25, N registered turboprop, within couterminous FAA airspace, under FAR parts 121 & 135 operating rules and performance wise, what are the requirements regarding computation of a suitable runway length as a function of airplane weight and runway surface conditions?

I'm pretty sure the answer is in the regs.

Each aircraft manufacturer is going to supply that data as part of its Aircraft Operating Manual. Operators must use these documents to determine required landing length, and this computation must be calculated during the planning phase of the flight by taking into consideration the estimated weight of the aircraft at the arrival time, as well as forecast winds, runway conditions and types of runways.
The regulatory "mandate" for doing these computations is found in the text of Parts 121.195 and 121.197, as well as 135.385 and 135.387. The relevant parts of each are pasted below, but the full text should be consulted for additional requirements and possible exemptions.

121.195. Detination Airport. no person operating a turbine engine powered airplane may take off that airplane unless its weight on arrival, allowing for
  normal consumption of fuel and oil in flight (in accordance with the
  landing distance set forth in the Airplane Flight Manual for the
  elevation of the destination airport and the wind conditions
  anticipated there at the time of landing), would allow a full stop
  landing at the intended destination airport within 60 percent of the
  effective length of each runway described below from a point 50 feet
  above the intersection of the obstruction clearance plane and the
  runway.

121.197.   Alternate airports. No person may list an airport as an alternate airport in a dispatch or flight release for a turbine engine
  powered airplane unless (based on the assumptions in §121.195 (b))
  that airplane at the weight anticipated at the time of arrival can be
  brought to a full stop landing within 70 percent of the effective
  length of the runway from a point 50 feet above the intersection of
  the obstruction clearance plane and the runway.

135.385. Destination Airport. No person operating a turbine engine powered airplane may take off that airplane unless its weight on
  arrival, allowing for normal consumption of fuel and oil in flight (in
  accordance with the landing distance in the Airplane Flight Manual for
  the elevation of the destination airport and the wind conditions
  expected there at the time of landing), would allow a full stop
  landing at the intended destination airport within 60 percent of the
  effective length of each runway described below from a point 50 feet
  above the intersection of the obstruction clearance plane and the
  runway.

135.387. Alternate Airports. No person may select an airport as an alternate airport for a turbine
  engine powered airplane unless (based on the
  assumptions in §135.385(b)) that airplane, at the weight expected at
  the time of arrival, can be brought to a full stop landing within 70
  percent of the effective length of the runway for
  turbo-propeller-powered airplanes and 60 percent of the effective
  length of the runway for turbojet airplanes, from a point 50 feet
  above the intersection of the obstruction clearance plane and the
  runway.


text:
How can I determine the amount of trim drag?
I fly an ASW27, which is a 15 meter glider with flaps.  I am flying with the CG at 62% aft.  I use down flaps while in a thermal and climbing; negative (up flaps) are used in cruise between thermals.  typical thermals speed is 50 to 60 kts (with ballast) and 90 to 100 kts in cruise.  This glider has a T tail and I need nose up elevator for thermal and nose down elevator for the cruise.
I notice that in cruise, the elevator is deflected down about 10 deg.  Is that deflection creating a significant amount of drag that could reduce my glide performance?  I have the ability to move the CG by dumping the ballast in the tail tank

I would think that you could determine some of that empirically by trimming for your selected glide with full ballast and with the ballast partially dumped to determine which is giving you a better glide descent ratio, which is going to be related to the total drag on the airframe.  Keep in mind that when dumping ballast out you are altering the total inertia of the glider which is also going to affect the glide ratio of the craft.  It may be that the additional drag penalty from trimming nose down is offset by the added inertia of the ballast.

An empirical determination can be done but such tests need still air.  Such air can be found early in the morning, or very late in the afternoon and during the winter months.  The effect of total ballast is well understood.  My question centers on the effect of the elevator deflection during the cruise portion. The deflection is in effect "lifting the tail" despite the negative lift normally created by the horizontal tail.

As I mentioned in my comments. You could test this empirically with the experiment described there.  If you find the additional ballast improved the glide performance of the craft, is there an aftermarket STC kit available which installs new ballast tanks in a more optimum position for a more neutral cruise trim?
I am a little concerned with the idea of continuing to move the CG aft of its current position in order to optimize the performance at the expense of. Asking the craft less stable about the lateral axis.  No increase in performance is worth your life.

The full range of the anticipated CG movement is known to be well within acceptable (safe) design limits of the glider.  The aft most CG position under consideration is still well forward of the aft design limit.

The glider has both wing tanks to carry water which is to increase the total weight as well as a tank in the tail fin which compensates for the forward shift in CG due to the wing tank ballast.  All tanks can be emptied in flight, which is usually done prior to landing.  The design provides acceptable flight characteristics with any level of ballast.

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text:
What can a new student pilot do on their own to prepare for class and instruction?
What is the best way to start for beginners learning to fly? I have a class set up and a instructor but not for another week or two. I just want to know if there is anything extra that I can start now, so it will become easier. I have started reading about the basics to get my mind going.

Welcome to Aviation.SE! The most important part is to relax, have fun, and ask questions. Don't overthink your first flight. Also don't be afraid to find another instructor if you don't meet eye-to-eye, better to do it at the beginning than in the middle. Personally I took Sporty's ground school course and found it very helpful.

Possible duplicate of First actual flight lesson, what to keep in mind?

Usually the best way is to call your local flight school and ask to take a discovery flight.  It’s a 30 minute or so flight in a Cessna 172 or similar aircraft and you’ll get a good introduction to flying, even some stick time in the airplane.
If you’re looking for material to read on the subject of learning to fly, I suggest getting copies of the pilots handbook of aeronautical knowledge, and the airplane flying handbook. Both are available for free as PDFs on the FAA’s website.  They will be the fundamental textbooks for your private pilot training and most of the knowledge and practical information on flying that the FAA will test you on are going to come from these documents.

awesome!,will do,  thanks! yeah i flew up in a piper sport the other day for my first time, also i got to move around the stick for a minuet in the air in Santa Monica, but thank you for your help. much appreciated!

the flight simulators available now are pretty good, these are fun and will get you used to the cockpit environment.

For getting used to the cockpit environment, just use your favorite search engine to pull out photos of the cockpit of the airplane model in question. A PC flight simulator at this stage might even be counterproductive. Remember that the instrument panel layout can vary significantly, not only between old-school instruments and glass cockpits.

Books Links:
https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/
https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/

There are two ways to approach this, much like learning a language.
One is to just jump in. Be like a sponge, soak up all around you and enjoy it as much as you can. Everything new is thrilling, and beginning to fly particularly so. This is like learning a language by moving to a different country and living there.
The other way is more … let's say cerebral. You will read a lot and learn things systematically. You will build up a theoretical base which makes - once you start flying - every experience more understandable and helps to confirm the theory. People who have learnt flying the first way will be stuck with oversimplifications and outright wrong explanations.
Which way to pick depends on your personality. Most people will go the first route and never look back. For me, it was always important to really understand what is happening. One of my flight instructors told me that I was his only pupil who discussed the phygoid motion during an aerotow. But seeing for real what I had only found in books before was deeply satisfying for me.

There's a third way: Study the theory (which in this case means textbooks and -- hopefully -- prod the others in the class, not least of which the instructor/teacher), and spice the theory throughout your classes with some actual flying. Being able to talk to your flight instructor and put the theory into practice while it's still fresh in your mind can be a great way to learn for some. Don't understand phugoid oscillations and how they feel? Ask the CFI to show you something like one, then take over control and try to settle the aircraft into level flight faster than it would on its own.

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text:
With positive passenger/bag matching rules, what happens to a bag that does not arrive with the passenger?
According to one answer to Why offload bags for missing passengers when flights are allowed to carry unaccompanied non-PAX air-cargo in holds?, the requirement for Positive Passenger/Bag Matching was introduced in 1988 following Pan Am 103. According to another answer to the same question, airlines cannot accept cargo from the general public.
Yet on a number of occasions when I've flown commercially as a passenger (including once to the US in the summer of 2001), for one reason or another my/our bag(s) have ended up somewhere else, or at the very least, not showed up on the conveyor belt at the destination airport along with the other passengers' bags.
What usually happens at that point is a conversation with an airline representative, and possibly one's card issuer or other travel insurance provider; and the bag arrives a day or two later. For the passenger, that's an inconvenience, but thankfully not usually a disaster.
However, what happens to the bag in the interim in such a situation?
Clearly, the bag very likely wasn't on the same plane as the passenger. This could mean one of two things:

The bag was not loaded onto any airplane (so it's still at the origin airport).
The bag was loaded onto some other airplane (so it's somewhere else).

The case of the bag not being loaded onto an airplane is strange, but doesn't seem to violate the requirements of PPBM; it's just sitting in a cargo holding area somewhere. If the bag was actually loaded onto some other airplane, that would violate PPBM, since there's no passenger on that flight accompanying the bag. (That said, I don't know if it would be possible to exploit this as a security weakness. Probably not, at least not reliably.)
Once the bag is found, it needs to get to where the passenger is now. I can see two basic ways to do that:

The bag is moved by ground vehicle (car, truck, boat, ...).
The bag is moved by airplane.

Driving a potentially long distance potentially just to get a single bag from one location to another seems the less reasonable alternative (it could probably easily cost a significant fraction of the profit from that whole flight), but on the other hand, if the bag is loaded onto an airplane, it definitely is a bag travelling without an accompanying passenger and in this case, it's known as such to the airline, thereby seemingly violating the requirements of PPBM.
If it were to be shipped as cargo, that would presumably qualify as "from the general public".
This seems to me like a "damned if you do, damned if you don't" kind of situation. So what really does happen to the bag, from when passenger and bag are separated, until the two are reunited?
For simplicity's sake, let's assume that what's inside the bag is completely innocous.

I'm confused. How is this not about aviation? True, it's about baggage handling, but it's about the airline side of baggage handling, not the passenger side, and it pertains to regulations (specifically PPBM).

It becomes freight. Airlines fly lots of freight (on passenger flights) without passengers, there is supposed to be a more vigorous checking process.

This is more a guess:
Think about the rationale behind the rule. A terrorist should not be able to send a bomb on a flight while staying at home. With this rule, a terrorist is forced to sacrifice himself by taking the same flight. Hopefully, most terrorists don't like this idea.
If the luggage wasn't put on board, or was put on another flight, the terrorist will notice this at the destination, and not before. Same effect, he had to be willing to sacrifice himself by boarding the aircraft.
So, the rule is not to never let luggage fly alone, it is about not letting it fly when the owner for some reason does  not take his flight.
If the luggage took another flight, it was for sure an error. The barcode scanner mis-read the barcode, the ID of the trays transporting the luggage was not read correctly, a computer error or whatever. Should not happen, but does from time to time.
If the luggage did not fly at all, it might simply have missed the flight due to technical / logistics problems. Or the barcode tag was ripped off etc.

Guesses would IMHO be more suited as a comment instead of an answer.

It may have been phrased as a guess but this is the actual reason. Cases where the bag flies on a different flight for reasons beyond the passenger's control are not a problem, especially if they happen rarely. The potential bomber still has to take the (very high) risk that he will be on the same plane as the bomb.

So your answer to "what happens to the bag?" is "exactly the same things as if the passenger were travelling with their bag on the modified route"?

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text:
How can angle of attack for a T-tail configuration be 21 degrees without stalling and also be flying at its trimmed condition?
I was reading a paper that looks at deep stall for T-tail configurations, and figure 2 suggests that the first trim condition for the aircraft in question occurs at approximately 21 degrees. Surely this would be a bad condition to fly at as it would result in stall due to flow separation over the wing, and if this doesn't occur the nose would be pointed so far up the aircraft would constantly be in climb? Excuse me if I'm missing something fundamental here. I've linked the paper here: https://research-information.bris.ac.uk/ws/portalfiles/portal/312655220/2022_SciTech_deep_stall.pdf

I would not take that graph too seriously - it is only meant to show the general principle.

The curve in figure 2 typically shifts up and down more or less proportionally to the elevator deflection. Most probably that particular curve has been drawn for an elevator with a quite positive (donwward) deflection. Pity that the source of the picture is not given.

@sophit As Peter pointed out, the graph is for illustration only, therefore it is described as "Typical pitching moment". It is an example the author drew himself (therefore no source) and most likely quickly drew himself.

@U_flow: I perfectly understand that. Anyway that is a scientific paper and if you make something up you should clearly write it otherwise people starts to wonder about the content, as this question demonstrates.

Thanks all, that clarifies things for me a lot more! :)

the first "trim" condition...occurs at 21 degrees

It's a shame they did not show the whole Cm vs AoA curve.
The aircraft is most likely already stalled here.
What they are showing is the overall aircraft Cm for various AoA if no control inputs are added, relative to a given AoA and trim setting where pitch rate = 0
One would expect positive Cm at stall for certain asymmetric airfoils$^1$, while many others remain negative$^4$.
The graph shows increasingly negative Cm (greater static stability) as the stall deepens and lift producing airflow over the wing collapses.  At this point the still unshadowed tail (and rear fuselage) is providing enough pitch down force (by way of basic longitudinal stability) to over come upward pitching forces of the forward fuselage and any portion of remaining wing lift ahead of the CG.
Deep stall occurs (Cm > 0) when turbulence from the wing greatly reduces the stabilator coefficient of lift.  The plane will no longer pitch down even though it's angle of attack is very high.
Cm remains positive until a second "stable" zone appears, but at a hopelessly high AoA.
It would behoof the engineers to provide enough stabiliator control authority to keep Cm negative post stall.  The model in this study may have been purposely created to be stall prone$^3$ in order to generate the graph showing the dangers of deep stall.
$^1$ even if the Cm of the wing remains negative, an increasing Cm, combined with the trim setting of the tail, can cause an aircraft to become staticly unstable as pitch increases.  Wing sweep with wing tip washout$^5$ can greatly improve pitch stability$^2$.
$^2$ Slats are also a great way to enhance the safety of swept wings in high AoA situations by increasing wingtip "downwash" (lowering local wingtip AoA).  Stalls on swept wings usually start at the wing tips, causing Cm to go positive, leaving the stabilator as the last line of defense.
$^3$ exceeding aft CG limits is an excellent way to do this
$^4$ a benefit of "olde tyme" undercamber, which can be created with a setting of slats and a little flap
$^5$ early Dunne D.8 aircraft criticized as being "too stable"

The value of the pitching moment coefficient only shows how far the airplane is away from a trimmed condition. To learn about stability you need to look at the derivative over lift coefficient or angle of attack. A negative derivative shows positive static stability.

@PeterKämpf I agree with that, and it highlights the need for (available) control authority beyond trim.  Thankfully, the graphs help me while I continue to learn the calculus.


text:
The phase having the hightest TIT for a flight mission
I have a query concerning the turbine inlet temperature (TIT) in the context of various flight mission phases. Specifically, I'm trying to ascertain at which phase the gas turbine reaches the highest TIT.
My understanding is that maintaining consistent thrust as the aircraft gains altitude requires an increase in TIT. Consequently, it would seem plausible that the highest TIT occurs at high altitudes where the aircraft needs to maintain cruise thrust.
However, I'm also aware that the takeoff phase, which necessitates the most power, may also demand the highest TIT.
Could anyone with expertise or knowledge in this area clarify this for me? Any input would be greatly appreciated.
Thank you in advance, and I hope you're enjoying your Sunday!

Are we to take into account effects of supersonic flight?

Do you count engine start as part of a flight mission?  Because that’s when it peaks.

No, my intention is to start counting from the taxi-out of a standard commercial aircraft not capable of supersonic flight.

Ok.  Common sense says it would be during the takeoff roll.  (High power setting, lower airflow). What sort of correlation to fact or data would make for an acceptable answer?

Thank you for your input. Would you be able to provide any data sources or freely accessible journals that corroborate this? Specifically, I'm interested in information about standard commercial aircraft like B777 and so on. Your help would be much appreciated.

The highest ITT/TIT/EGT is always seen as brief transient during start, during initial takeoff thrust setting, or during slam accelerations (go-arounds). On the General Electric CF-34-3B1 (the engine used on most Regional Jets and originally developed for the A-10), the max ITT is 900C, which is allowed for brief transients during starting, slam accelerations, or during takeoff (up to 2 minutes).
Outside of those conditions, you are limited to the Max Continuous Thrust temperature limitation (the normal climb thrust setting). On the CF-34, this is 874C.
On a fresh engine, temperatures seen will normally be well below these values when the fan RPM is at its limit (98.6% N1 for Max Continuous on the CF-34). This is called "ITT/TIT/EGT Margin" and is the main engine health condition indicator.
As the engine wears, temperatures creep closer to the limit values as efficiency declines, and eventually you start getting overtemps on start, or you can't achieve rated TO thrust or Max Cont thrust fan speeds without exceeding the temperature limits, and the engine is ready for overhaul.
But in any case, you will see the engine get pretty close to temperature redline during starting (less so with FADEC engines that manage the start fuel flow much more precisely, and will even auto-shutdown if there is an exceedance), and you may see it very close to that when setting TO thrust with a tired engine, but beyond that the temperature values are always lower for climb thrust, and lower still for cruise thrust, simply because you aren't putting as much fuel through.

Thank you very much for your detailed explanation. :)


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Why does a turbine engine compressor ratio affect stagnation pressure?
This might just be a misunderstanding on my part, but in an ideal Brayton cycle, the flow through the compressor and turbine is isentropic, meaning $\Delta s = 0$. However, usually you are given the compressor pressure ratio to calculate the exit stagnation pressure, i.e.
$$
p_{cr} \equiv \frac{p_{03}}{p_{02}},
$$
where station 3 is the exit and station 2 is the inlet. This makes completely no sense to me. In an isentropic process, the stagnation pressure is constant, so I don't understand how there can be a ratio. I do understand that the pressure increases in the compressor due to compressing the air and increasing the temperature, but these two points of view seem to be contradictory.

By stagnation pressure I assume you mean total pressure. Stagnation is not a term commonly used in gas turbine engine performance, it’s more common with aerodynamics. The compressor increases the total pressure because the rotating blades are doing mechanical work on the fluid.
A couple of other comments, to explain in more detail;
First, the flow is not isentropic in a compressor. It only would be if a compressor was 100% efficient. The efficiency is actually calculated by the degree to which it is not isentropic. The efficiency is given by the isentropic temperature rise that would occur for the given total pressure rise, divided by the actual total temperature rise. An efficient compressor obtains the same pressure rise, for a smaller temperature rise. While you might think a higher exit temperature would be good, because it would mean we could burn less fuel, a greater temperature rise across the compressor would require more shaft power to compressor the air, which is taken from the turbine and means the turbine exit gas is now cooler and a lower pressure and now cannot produce the same thrust.
Secondly, the stagnation pressure is not constant (even if it was 100% isentropic). This maybe the case in a fluid flow where no energy exchange is occurring, but in a compressor, the rotating blades are doing work on the fluid. This increases its total pressure. The area at the entrance and exit determine its velocity (along with its density). Different areas, changes in density, and total pressure mean the static pressure isn’t the same at the entrance and exit, either.

I suspect you were trying to match the realities of an actual jet engine with the ideal conditions of a Brayton cycle.  It’s kind of like pointing out the air is, in fact, not an ideal gas.   Well true the behavior of each of those things is very close to the ideal models that we created for them

A compressor uses a shaft’s rotational energy to convert a slow moving or stagnant air stream to a high pressure stream. A turbine on the other hand uses a high velocity air (or water) stream to make a shaft rotate in order to generate shaft power for a number of uses, mostly for electricity generation, but as in planes part of the energy generated is used to power the compressor in the same jet engine.
Another way to look at it is this: energy is put into a compressor while in a turbine, energy is the output. Also for a compressor, a low pressure stream of air goes in but a high pressure stream comes out. In a turbine, a high pressure stream goes in and a low pressure stream comes out.
A more detailed explanation requires first understanding the zeroth and first laws of thermodynamics.
Note that compressors only work with air, the equivalent for water or other liquid is a pump.


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How can I determine specific heats of gases for turbojet engine calculations?
I'm in a combustion lab and we are performing experiments on a turbojet engine. However, I am having some trouble calculating the exit velocity and compressor/turbine powers of the engine.
Consider the nozzle exit, where the exhaust gases go. Assuming 100% adiabatic efficiency of the nozzle and applying the 1st law of thermodynamics gives
$$
\frac{u_e^2}{2} = h_{0e}-h_e = c_{p,N}(T_{0e}-T_e)=c_{p,N}T_{0e}[1-(p_a/p_{0e})^{(\gamma_n - 1)/\gamma_n}],
$$
assuming $p_e = p_a$, the ambient pressure. In the lab, we've set up thermocouples that measure the stagnation temperature and pressure at the exit, as well as ambient conditions. My problem, however, is that I have no idea where to get $c_{p,N}$, the specific heat of the gases in the nozzle from. I've looked up in a reference book that the average specific heat ratio $\gamma_n = 1.36$, but this still doesn't give me the specific heat that I need because I don't know the specific gas constant $R$ for these gases. For reference, it is an SR-30 turbojet with Jet-A fuel.
In addition, I have the same problem when calculating the power outputs. Assuming that all of the power of the turbine is transmitted to the compressor,
$$
\dot{W_T} = (\dot{m_a} + \dot{m_f})c_{p,T}(T_{04}-T_{05})=\dot{m_a}c_{p,C}(T_{03}-T_{02}) = \dot{W_C}
$$
Again, I have no clue what the specific heats are, only their ratio. Is there some way I can calculate these quantities or look them up somewhere? Or even find the specific gas constants somewhere?

R or R* is the Universal Gas Constant, 8.3143 joules/K-mol. The gas constant r for a particular gas, or the specific gas constant is calculated as r = R/m where m is the molecular weight of the gas in question.

Do you have a copy of the book Gas Turbine Theory by H. Cohen, G.F.C. Rogers and H.I.H. Saravanamuttoo? You may well find the answers in there I think.

Yes, they are on the back page. But, here’s a website with them: https://www.ohio.edu/mechanical/thermo/property_tables/air/air_cp_cv.html Walsh and Flecther’s book Gas Turbine Performance is also a great source for this sort of info. See https://www.amazon.com/Gas-Turbine-Performance-Philip-Walsh/dp/0791800679

Alright guys, I’ve found cp for the compressor and turbine. My next question is would the nozzle cp be the same as the turbine cp since the same gases are flowing through them? I can’t seem to find cp nozzle in any of the references you gave.

@JoshPilipovsky.  cp (and cv) is a function of total temperature, and fuel air ratio. In a civil engine, the FAR and total temp in the exhaust nozzle is the same at the low pressure turbine exit. But, it will be different to the value at the HP turbine entry, or LP turbine entry, as total temperature is decreasing through the turbine as energy is extracted. If your engine includes an afterburner which is operating, that will change the FAR and total temperature between the LPT exit and nozzle. Use the formula for cp and cv as a function of total temp and FAR as outlined in ...

...this paper here: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1015.6142&rep=rep1&type=pdf

Well known values used in manual gas turbine calculations for the specific heat for air are 1005 J/kg/K and 1150 J/kg/K for combustion gasses. However, note that these are chosen values that are convenient for the calculation, these have no value when considering the actual gases.
The specific heat (at constant pressure, $c_p$) of gases depends on the composition and the temperature. This implies that your calculations are always incorrect using the formulae expressed in the equation. You need to integrate over the compression or expansion process.
It is possible to calculate the specific heats, note that Gordon and Mc Bride from NASA Cleveland, Ohio have shown how this can be done through a computer program: Computer Program for Calculation of Complex Chemical Equilibrium Compositions and Applications, known as CAE. The calculation is based on polynomials calculating the individual contributions for the species in the gases (to make the polynomial dimensionless, it is given in the form of $\frac{C_p}{R}$).
$$\frac{c_p(T)}{R} = a_1T^{-2} + a_2T^{-1} + a_3 + a_4T + a_5T^{2} + a_6T^{3} + a_7T^{4} $$
In this equation the constants $a_1$ through $a_7$ are defined below and above 1000 K. The $c_p$ found using this equation is in (J/mole/K). To get $c_p$ in (J/kg/K), one can use the molar weight of the specie. The $c_p$ of a mixture is calculated by taking the weighted average between the values of $c_p$ of the species present in the mixture. In case of a $c_p$ in (J/kg/K) the mass fraction is to be used and in case of $c_p$ in (J/mole/K) the mole fraction:
$$ c_{pg} = \sum_{i=1}^{NS} ({m_i \cdot c_{p,i}}) = 1 $$
where:

$c_{pg}$ = specific heat at constant pressure of the (gaseous) medium (J/kg/K),
NS = number of species in mixture (-),
$m_i$ = mass fraction of specie $i$ (-),
$c_{p,i}$ = specific heat at constant pressure of specie $i$ (J/kg/K).

The specific heat used in gas turbine performance simulation software used to be tabulated based on the fuel to air ratio (FAR) of kerosene in air. Using interpolation, the values for the calculation are found. However, more complex and modern gas turbine simulation software tools have some sort of an implementation of NASA's CEA.

Find and old Pratt & Whitney handbook. It list k values for combustion products of alkanes at 100% stoich, 200% stoich, and 400% stoich.


text:
Flying VFR in uncontrolled airspace, what to do if one spots an apparently out-of-control fire on the ground?
Suppose I'm flying VFR in class G (uncontrolled) airspace, monitoring the local CTAF frequency while doing so. Maybe I'm alone in doing circuits around the local airport, or maybe I'm practicing navigating by landmarks, or maybe I'm on a cross-country flight from A to B. Either way, there is no one else in the immediate vicinity making themselves known on the radio, and (unlike in controlled airspace) there's no obvious ground station that I can call and expect to get an answer from.
Now, I, or someone else onboard, spots a fire on the ground some distance away.
A good first step then seems obvious, to go closer to get a better look. Now suppose that, on closer inspection, this does indeed appear to be an out-of-control fire with no firefighters on site. This could mean either that nobody yet knows about it, or that rescue services have been alerted but are still on their way.
It could be a structural fire, or a forest/field/grassland/etc. fire. To the extent that this makes a relevant distinction, it'd be great if answers addressed both types. (Both of these have happened recently in my immediate area, though I don't think they were initially reported by aviators.)
For me, a thousand feet or more above ground, what's the next step?
The aircraft isn't in any immediate danger, so from the perspective of the aircraft and its occupants, it's not an emergency or even urgency situation. However, there's certainly risk to property, and possibly people, on the ground.
Should I dial in 121.5 on the radio and call mayday? Or pan-pan on 121.5? Or should I use some other frequency, such as that of the local area control if I were to climb straight up into controlled airspace? (They would also be monitoring 121.5, so I would effectively be reaching the same people.) Mayday, pan-pan, or not? Or something else entirely?
Not doing anything in particular and just going on with my day doesn't seem like the right thing to do in such a situation.
Looking at my radiotelephony textbook, urgency traffic (pan-pan) includes situations relating to the safety of a "vehicle" (not just the aircraft, but specifically including any aircraft) or for a person onboard or within sight, but that do not require immediate assistance. Emergency traffic (mayday) includes situations involving "serious and/or immediate danger" (unspecified as to what) where immediate assistance is required.
I'm interested primarily in answers pertaining to the EU.

Are we talking about a forest/field/grassland fire here, or a structural fire?

@UnrecognizedFallingObject Good point. I pretty much had in mind both, but have edited to clarify that.

As a marine radio operator, I'd use a Securite call to convey information of safety importance to others.  Not sure whether that's equally well understood in aviation, though.

And I think times have changed.  Not that long ago, a call to a controller at an ARTCC might be met with "um, so?"  Whereas the last 10+ years there's become a much greater appreciation about how a localized fire can quickly become a regional disaster costing lives and many millions in damage.  So you are much more likely to get serious interest now.

This has happened several times and each time I was able to reach a local approach facility.  Prior to GPS, I would circle above the event, and approach would get a pretty good fix.  One time it was a propane facility near the uncontrolled airport I was flying out of at night.  Shortly there after, when the flames shot above 4500 feet, the tower saw it form 20 miles away, visually.
One of the more interesting events was one early spring, when I was crossing the Finger Lakes in New York, and saw two snowmobiles go through the thin ice.  I hung around for the recovery, and everyone was pulled out of the water alive.  In that instance, (Rochester) approach kept asking for updates, as they were talking with the fire departments, who were trying to find the best ice for their approach to the snowmobilers.
In my experience, I have always been able to reach approach.  However if approach was not available, enroute or FSS, and as a last resort, local unicoms.
When flying for the state conservation department, we did radio in fires, as part of the job expectation.
For those looking for more guidance, might I suggest something like:
Cessna345: Approach, Cessna 12345, 20 miles south, near Geneseo VOR, with two snowmobiles through the ice on the lake, 5 miles southeast of the VOR.  Three souls observed in the water.
Apch: Cessna 345, squawk 4311, ident, say altitude.  How long ago did this happen.
Cessna345: About 2 minutes prior to my call up. 1500.
Apch: Any other snowmobilers in the area?
Cessna345: No, not at the north end of the lake.
Apch: Fire is being dispatched from both sides of the lake, would you say the swimmers are closer to the east or west shore.
Cessna345: East shore, advise fire that I am circling above the swimmers, with landing lights on.
and so on.
Addendum: The question asked about uncontrolled airspace, and while there may be uncontrolled airspace even in areas of radar and ATC coverage, it is useful to discuss what to do when ATC coverage is more sparse.  The objective is to communicate to authorities so that fire services can be dispatched to control the fire, and alert people who might be in harms way.  My suggestion, as a CFI and as someone who has flown the northeast corridor as well as rather desolate portions of the earth, is to establish communication with anyone on the ground as soon as practical.  If you can reach any FSS or ATC facility, I would contact them first.  If unable, and if nearby (considering your altitude) I would try airports with unicom/multicom frequencies listed.  You might alter your flight to get you closer to civilization and potential contact points. In Northern Canada, as an example, there are many well equipped airports which are not charted, but support mining operations. I carried a list of their frequencies shared with me by regional pilots.  Barring that, I would make calls on 121.5.  There may not be any facilities around which are in range for 121.5, but there are likely airlines and military flights which monitor 121.5, particularly in cruise. It is not uncommon to use other aircraft to relay information, and short concise messages help.  If one has HF or a SATphone, then the radio game is different.  In extremely sparse areas, a fire may only be of advisory interest, so do not expose yourself to increased risk to report it.

I ended up asking my instructor about this.
His answer: If you aren't already talking to ATC, then switch to whatever frequency Control can be reached at in that location at the lowest controlled airspace altitude (which in the case of Sweden typically means whatever the local frequency for Sweden Control is at 5000 ft AMSL and above), climb in place if necessary to reach them, and make a normal transmission (not "mayday" or "pan-pan") letting them know what's going on and where, and take it from there.
The general rationale is that the aircraft is not in any danger, so it isn't justified to call mayday or pan-pan. Since the aircraft is in class G airspace, it's likely also away from the nearest controlled airport, so the controllers handling the airspace around the nearest airport are unlikely to be able to help more than those at Control. (Of course, if one needs to climb through controlled airspace to reach Control, it's probably worth talking to whoever controls that airspace.)
It's certainly possible at that point that Control might hand you off to a more local controller if they make the determination that doing so is beneficial.

I think a Mayday would be appropriate if smoke was obscuring visibility, especially if you're not IFR qualified - the same way suddenly flying into a cloud might be. If you can't see, you're liable to get inverted and fly into the ground.

If you're just wandering around VFR in uncontrolled airspace in the boonies, I would call in on whatever frequency is used for VFR enroute purposes in the EU and tell them what you are seeing and where it is, and go on with your day. If you are out of radio range but there is cell phone service, then call whatever regional control or flight information unit is applicable and tell someone.
Definitely not a Mayday (generally means you're about the crash, and people will get very excited) or PAN (which means you have something urgent that is flight related and needs priority over other communications, and people will get a little bit excited).  A possible forest fire on the ground doesn't come to that level in my opinion.

"whatever frequency is used for VFR enroute purposes" would be the local CTAF, which we already established at least doesn't have anyone else actively making themselves known. It's much easier when you're in airspace that requires two-way radio communications; just call up whoever you're already talking to and let them know.

Well, I suppose if it's serious enough you could broadcast a call on 121.5 and say "PAN PAN PAN xxxx on guard frequency" .  Chances are an airliner in range will answer. ("guard frequency" tells whoever hears it you are knowingly broadcasting on 121.5 for non-emergency purposes).  I would do that before breaking in on an enroute IFR frequency.

I have no idea what you mean by "enroute IFR frequency". Controlled airspace here is basically anything above 5000 ft AMSL, and significant chunks of airspace lower than that near a lot of airports. There is no requirement to fly IFR there, but anytime you're in such airspace there's obviously a specific ground station that you're already in contact with. That's not the point of my question. The question is what to do when there isn't an obvious ground station to talk to, yet you encounter something unrelated to your flight which likely warrants a response from emergency services.

I meant if there was no VHF ground station in range because you're in a remote area, but there was the possibility of climbing and contacting an area control center that is handling IFR enroute traffic.  Anyway, so if you are out of range of VHF communication with any kind of VFR facility, cruising along in the middle of nowhere, well the answer is nothing until you get to where you can, or when you can use your cell phone.

There is no need for "PAN PAN", but you can use 121.5. maybe something like "121.5 N12ab3 at 4000ft, reporting large [structural, forest, grass, etc] fire on the ground near location xyz." wait for a response and refine the location.

Keep it simple, 121.5 can be used for this rather than fumbling through a list of possible frequencies. People get the idea that 121/5 is "emergencies only" but far from it 121.5 is for all occasions when you don't know the local frequency and time is a factor. Something like "121.5 N12ab3 at 4000ft, reporting large [structural, forest, grass, etc] fire on the ground near location xyz." wait for a response and refine the location. As this is aviation, the initial XYZ should probably be a published fix or waypoint just to quickly narrow down the sector.
If you get no response then try to find an approach or center frequency on a chart (many GPS will list nearby options) and try that. Flight-service stations [where you would file a flightplan in the air] are another option, while most connect to an operator many states away they can relay the information or provide you with a local frequency.
Include what is on fire and approximate size, it is possible that the burn is actually permitted and more controlled than it appears. Just give the location as accurate as possible, use major visual landmarks, distance and radial from a VOR, lat and long(paper chart or gps), as much as you can muster.
I have reported fires to a local control tower on the normal tower frequency as I was already communicating with them to enter their airspace, and in this case you may get the benefit of radar contact for the position.

Who you call doesn't depend on whether you're in controlled airspace, but whether you can reach them may. Call whoever you would call for anything in that general area, and if they can't hear/see you (usually why airspace is uncontrolled), then climb until they can.
Even if there are ground forces on the way to deal with the problem, you should still report it to ATC/FIS if it presents a hazard to navigation due to smoke, severe updrafts, etc.
If there is no ground response, you might also call 112/911/999/etc on a cell phone, if you're getting a signal, and be ready with the lat/lon since they likely won't understand other aviation lingo.

I think I'd definitely find someone to talk to that could relay the information to the police/state police and let them work it on the ground with the appropriate fire department.  Approach nearest the fire might be a good start. Class D, Class C, Class B area might be good. Lot of those in my area, my airport is under a Class B 30 mile veil for example, I talk to approach all the time for going anywhere.

In the USA:  I'd personally start with Flight Service: 122.2.  Especially during VFR weather, they usually don't have a lot going on; they're not directly responsible for traffic, and can figure out how to call local fire/police.


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Are winds that are not from the prevailing wind direction more often gusty, and why?
It seems to me that, looking at the ground weather forecasts (as opposed to, say, low level forecasts), it's far more common for the wind to be predicted to be significantly gusty when it is blowing across the runway direction of my local airport, than along with it.
Now, obviously, the wind doesn't particularly care about the direction of the slab of asphalt on the ground, but the slab of asphalt is normally aligned with the prevailing wind in the area.
Is a wind that blows at a significant angle to the prevailing wind direction more likely to be gusty, than a wind blowing in the prevailing wind direction in the area? If so, what's the mechanism behind that? Or is this just a case of me being more frustrated about gusty crosswind conditions, thereby noticing it more?
My area is relatively flat.

To clarify, since there seems to be some confusion about this; I'm referring to area ground-level weather forecasts intended for the general public (as those offer a longer-term outlook, typically with reduced resolution and accuracy up to ten days ahead), not METARs or TAFs (however presented) which are about weather conditions specifically at the airport now and in the next several hours.

Are you talking about a mixing winds condition where two wind patterns converge?

A little more info about where your airfield is would be helpful.
The generic answer would be that a significant weather event would be required to over come the prevailing winds.  Also, as winds changed from prevailing to cross, gusts and shears would be more likely.  Local low level factors such as terrain, buildings, and trees may also taken into account. The airspace along the runway is generally more clear of these effects as compared with across it for a single runway.  Larger airports with multiple runways provide more options.

Well, the ground forecast isn't just for the airfield, it's for the area, so I doubt the factors you mention would have a significant impact on it. They probably do locally, as in, say, within the immediate vicinity of the airport, but there are both trees and buildings to any direction of an arbitrary point, so for the area, it seems like those effects should effectively cancel out.

My training field was 280 to 100.  We almost always took off from 280 into prevailing northwest winds, which generally meant clear skies.  Southeast winds, or especially northeast, generally meant storms or unstable air. I can only remember taking off on 100 a few times.

You need to know what causes air movements to better answer this question.
Generally, there are two sources: Earth rotation and sunshine.
Earth rotation leads to large-scale air movements from Coriolis forces. This is the source of prevailing and less gusty winds. Local obstacles can still cause local changes in direction and even regular gusts from a vortex street, but that is rather unusual.

Vortex street behind the Juan Fernandez islands (picture source)
Sunshine will heat the ground which in turn heats the air above it, reducing its density. Periodically, this heated air will bubble up as a thermal and cause surrounding air to flow towards the thermal, being felt as a gust by an observer. Typical sources of thermals can be the edge of a forest or a local hill which will give the heated air a jump start.

Is a wind that blows at a significant angle to the prevailing wind direction more likely to be gusty?

If you observe the gusty conditions in fair weather with lots of sunshine, small cumulus clouds and from late morning to late afternoon? Then the answer is yes. The gusts are caused by thermals - look for typical sources of thermals to understand where they blow to.

Here is O'Hare's wind rose for 1961-1990.

So Chicago's prevailing winds are prominently southwesterly.

NOAA's historical data for Chicago
for the past year, 2018 Sep 28 to 2019 Sep 28, includes:

WDF2, direction of fastest 2 minute wind (degrees)
WSFG, peak gust speed (mph)
AWND, average wind speed (mph)

The first approximates daily wind direction.
Dividing the last two approximates gustiness.
Here's the resulting scatter plot of direction vs. gustiness.

Other than extreme gustiness when the wind is due north,
this shows no strong correlation.
Winds from the ESE (120 degrees) are rare (fewer X's), as confirmed by the wind rose.
Winds from 180 to 270 degrees are more frequent (denser X's), as confirmed by the wind rose, but they're not gustier.
I don't see any other conclusions to draw.
Plotting gustiness redefined as the mph difference between peak gust speed and mean wind speed, instead of the ratio, leads to the same conclusions.

Is wind at a significant angle to the prevailing direction more likely to be gusty?

No, at least not for Chicago in 2019.  (The data for all of Illinois was too big to download.
Smaller Illinois towns lacked some of these fields.)

Or is this just a case of me being more frustrated about gusty crosswind conditions, thereby noticing it more?

I think that is the case.  Are there trees along the length as well, making for interesting wind rotor effects?


text:
What is the max landing altitude of the Airbus A320 family?
I know the Boeing 737's max landing altitude is 8,400ft standard and 12,000ft with the high altitude option. I am struggling to find the same figures for the A320 family. All I can find online is the standard of 9,400ft, but it is clear that Airbus offers a higher option as I can see A319's operating out of Daocheng Yading airport [ZUCD] at an altitude of over 14,000ft. Does anyone know what the actual certified figure from Airbus is? Thank you.

Maybe related: https://aviation.stackexchange.com/questions/93036/what-does-the-high-alt-landing-guarded-push-button-on-the-a320-exactly-do

For possible information see page 36: http://www.caac.gov.cn/ZTZL/RDZT/XJSYY/201511/P020151126413567294102.pdf

According to the EASA (EU Aviation Safety Agency) type certification of the Airbus A320 series (which you can find here), the A320 family is certified to land at airports with an elevation of up to 14,100 ft. Special procedures for such high altitude landings are described in a Special Conditions Annex (page 112) to the type certification.
This is (sort of) confirmed on Airbus's website: "the A320 Family is certified to operate in areas with altitudes of up to 14,500ft for both CFM and IAE engines".
So in the EU the A320 can legally land at a maximum elevation of 14,100 ft, in other parts of the world up to 14,500 ft.

Is the limit based on elevation or on pressure/density altitude? As far as I know there are no airports (at least public/commercial ones that an A320 would land at) in the EU above 14,100' and none at all above 14,500'. So the limitation seems moot.

@TypeIA Presumably they need to set a restriction anyway, just in case someone decides to build such an airport in the future.

@Chris-RegenerateResponse I get your point, but realistically there are only so many places on Earth that are high and flat and big enough ;)

@TypeIA Because safety should be based on "dangerous until proven otherwise", not the other way around.

I would guess it's so that EASA can make sure aircraft continue to meet safety requirements while operating outside EU airspace.

@TypeIA Hellicarriers :)

It is not about the operation in the EU being limited to landings at 14,100 ft. It is aircraft operated on a Type Certificate provided by EASA, no matter where in the world they operate. The Chinese CAAC has their own airworthiness certification of the A320 which is mostly based on de EASA certification, but with deviations specific for the Chinese situation.

Could an airport be built at 30k feet though?: https://aviation.stackexchange.com/questions/67953/would-building-an-airport-at-30-000-ft-save-money


text:
Does the Attitude Indicator Face Card Move?
I'm trying to better understand how the rigidity in space principle works in relation to the attitude indicator. My understanding is a gyroscope is a spinning disc that is able to maintain orientation and not be disturbed (when spinning fast enough sort of like a toy top).
My understanding is that the gyroscope in the attitude indicator is supposed to stay upright to maintain orientation to the natural horizon. Where I am confused is what is actually moving on the attitude indicator (if anything) when the plane pitches and banks.
Does the attitude indicator face card move as the airplane pitches and banks and the gyro simply helps the face card to maintain a relative orientation to the natural horizon? Is the face card fixed and we are simply rotating around the face card as we pitch and bank the plane? Is the miniature airplane fixed or is it moving as well?
Hope my area of confusion is clear - just trying to get a dumbed-down explanation of what is going on with the instrument as the airplane moves. Thank you!

This might help

A good reference is the FAA Pilot's Handbook of Aeronautical Knowledge Chapter 8 "Flight Instruments".
The attitude indicator card is mechanically connected to the gyroscope, as shown in .  So, the gyro stays (approximately) rigid in space, as does the card.  The airplane (and body of the instrument) rotate in pitch and roll.
The "miniature airplane" is fixed to the body of the instrument at any point in time.  But, can be adjusted in height (pitch) with a knob, by the pilot, for different conditions (ie changes in fuel).
You can see different examples in this figure

Note that the labeled "adjustment knob" raises and lowers the "miniature airplane" reference.


text:
Can supercharger/turbocharger increase absolute ceiling
Superchargers and turbochargers can increase the service ceiling. Then what about the absolute ceiling? Can superchargers or turbochargers increase it?

You mean absolute ceiling?

@Sanchises oh yes. Thanks

"Then what about the absolute ceiling? Can superchargers or turbochargers increase it?" -- how could they not?

A turbocharger or supercharger increases the available power, and thus the climb rate, at all altitudes. The absolute ceiling is just where the maximum possible climb rate reaches 0 fpm, so increasing the available power at this altitude will raise the absolute ceiling to a higher altitude.

Although forced induction can increase the absolute ceiling from an aircraft performance point of view (the definition of the term), keep in mind that there may be other restrictions on the maximum altitude for the aircraft to fly at.
Presumably an aircraft with forced induction will have pressurized magnetos, but un-pressurized magnetos won't work beyond a certain altitude.
Cabin pressurization limits -- there are structural limits on how much delta-P you can sustain.  As you go higher (while maintaining a constant cabin altitude), this pressure will increase.
There are also procedural limits to cabin pressurization -- i.e. the regs say that in the event of rapid depressurization, you have to be able to get back down to breathable levels in a certain amount of time.  This generally prevents civil aircraft from flying above 45000 ft.  The Concorde flew at 60kft, but it may have had special dispensation.  These are higher levels than a piloted piston-prop aircraft would consider, but you get the idea.
As you go higher (say at constant equivalent airspeed), your true airspeed increases.  The air also gets colder -- which reduces the speed of sound.  Consequently, the Mach number increases.  The aircraft may start to encounter compressible aerodynamic effects -- first on the propeller, but the instrumentation, and wings will be affected.
Aircraft like the Golbal Hawk are simultaneously flying on the verge of stall, buffett, and compressibility effects.
So, yes you can increase the absolute ceiling with forced induction -- but don't forget all the other things that happen with increased altitude.


text:
Can I climb with no excess thrust
I've been searching on the internet about this question and all say you are not able to climb with no excess thrust. But I am wondering that if I have no excess thrust, can I still climb in exchange for slower airspeed?
Like I'm flying 150kts while having no excess thrust (idk if this is possible). Can I climb higher in exchange for 50kts?
"If you have no excess thrust, you cannot climb with constant airspeed. Speed will decrease if you climb. You will be trading speed for altitude."  Is the above statement correct? If not, correct me please.

To misquote (I expect) Trevor Thom, fuel will keep you aloft for hours, altitude for minutes and airspeed for seconds.  If you have excess airspeed (I.e. you’re above stall) then you can cash some kinetic energy in for altitude but it’s not going to get you very far.

Yes you can. By doing so, you are sacrificing the aircraft's kinetic energy (speed) to gain potential energy (height).


text:
Why A320/330 use C* FBW control without speed stability?
The A320 and A330 family are FBW aircraft that use C* longitudinal control laws for longitudinal sidestick command tracking. In essence, stick neutral commands 1G flight. When stick is deflected longitudinally, a blend of pitch rate and normal load factor is commanded to provide a consistent G-feel to the pilot; once the stick is released, 1G flight resumes, but the airplane is steady-state at the new pitch angle (or flight path angle to be more exact).
Unlike B777, B787 and A220, however, the A320/330 family do not have artificial speed stability. Once the aircraft is steady-state at the new pitch attitude, and with the autothrottle disengaged, the airspeed will settle to a new trim point. In another word, unlike a conventional aircraft, the A320/330 only has neutral speed stability.
This is why the envelope protections of the Airbus aircraft are not nice-to-have features, but essential features to ensure the airspeed does not rapidly bleed off to stall or increase to overspeed, all while the stick is neutral.
My question is, why is a C* control law without speed stability desirable for a transport category aircraft? The A320 does not need to perform precision target tracking as a fighter aircraft would, and it changes the flying characteristics drastically from those of a conventional aircraft.

Are you saying that the 320, if you are doing say 220 kt, and you pitch up 10 degrees keeping power the same, and the airplane slows to 180 kts and stabilizes there, it will now trim to 180 kt and if I make a power reduction without touching the stick it will pitch to maintain 180kt?

@JohnK The first part, yes. Reducing power does not nominally change the flight path angle and instead reduces the speed further. That's my understanding.

I had a chance to try out a C series (A220) development sim once and I remember that it was designed to behave like a normal a/c.  It has a trim speed bug on the speed tape and when you work the trim it moves to tell you what your new trim speed will be and will behave like you'd expect it to. Very convenient.  I know that Boeing's overall philosophy is more "pilot centric" whereas AB, at least on their early FBW, preferred to grant more authority to the computers.  Bombardier tried to split the difference on the C series, going with side sticks but trying to maintain traditional behaviour.

Don't know for sure but I would theorize that a system that maintains FPA would tend to make it easier to hand fly a glide slope, where the priority is to pitch to the FPA (the glide slope) instead of pitch to speed.  You just work the thrust for speed and let the computers take care of trim.  On a normal a/c it's a bit more work because you'll be pitching to slope and retrimming and managing thrust all at the same time.

Many accidents have shown over and over that once the handling becomes muscle memory, the cue that having to pull harder means you are losing speed is easily missed anyway, so it's not as important as it seems.
So the artificial neutral stability instead decouples the controls: stick for flight path angle, thrust levers or A/T for speed. Nice and easy and you don't have to fiddle with the trim button that most pilots end up pressing rather mindlessly.
Large aircraft tend to be flown with auto-thrust all the time anyway, including e.g. a 777 which is stable in pitch and has trim. And when they are, the logic is rather like Airbus—control column for flight path angle, maintain flight path angle when released, just after changing speed you have to fiddle with the trim to get it stable again, which Airbus Normal Law does for you.
Note that aerodynamically all Airbus aircraft are still longitudinally stable, so if the sensors fail and the system degrades to Direct Law, the trim behaves like in any other aircraft.

Do you have sources to back up your statement regarding accidents and static long stab? Static long stab requirements are written into the basic Part 23/25 rules and all the major OEMs, except for Airbus, have adopted the C*U-like approach. What of the case with maximum TLA applied, for max climb, for example?

@JZYL, not as an explicit statement. However note that there are still many accidents when pilots keep pulling up until the plane stalls despite the increasing force. Also note that the unreliable airspeed procedure does not utilize the trim, but simply defines pitch and power. Big part of the problem is that thrust setting, flaps and gear change the trim a lot, so the force is not really indication of your speed or your margin from stall in direct trim aircraft. It only does that in the Airbus alpha-limit mode.

@JZYL, note that the requirement only states that force to keep the nose up must increase when approaching stall, which Airbus satisfies with the alpha-limit mode.

@JZYL, maximum climb in Aibus is easy—set maximum continuous thrust and pull on the side-stick until the speed trend stops indicating increase. In direct trim aircraft with underslung engines (the typical configuration) you have to push the yoke when adding power to avoid stalling (at least one A310 crashed because the alpha-floor A/T logic added power and the pilots didn't compensate), arrest the phugoid oscillation and then re-trim for the new power setting, so you'll be referring to attitude and airspeed indicators anyway and not the feel anyway. The Airbus way sounds easier.

The static long stab applies to all airspeeds from 1.3Vsr to Vfc/Mfc (25.173). It's separate from stall characteristics. I assume A320/A330 got an ESF from the respective cert agencies.

I'm not sure I understand what you mean re- max thrust climb. On a C*U aircraft, you would set the trim speed; on stick free, the aircraft would climb at gradient per speed, while maintaining the trim speed. It's similar for a conventional aircraft, albeit without phugoid suppression. How would it work with Airbus?

@JZYL, on a C*U aircraft, you set the trim speed, but then you add power and throw the trim off. Airbus is completely different. In Airbus you set flight path angle with stick and it maintains it, so you have to watch the speed. But since on C*U aircraft as the power decreases, the trim changes, so you have to watch the speed anyway.

Makes sense for normal flying. However, wouldn't it be very weird flying back-side with C* only?

@JZYL, why? Only change on the back-side (of the power curve) is that now your speed is unstable, so the thrust levers need more adjustments, but most of the time the auto-thrust is handling them anyway.

On the backside, pitch control is needed to control speed. Seems awkward to me with a control strategy where the steady-state at 0 stick is constant pitch. But I suppose if C*U can do it, then so can a human adapt.

@JZYL the strategy is not constant pitch, it is constant flight path. You add power and the aircraft pitches down on its own to maintain flight path. You reduce power and the aircraft pitches up to slow down maintaining the flight path until it gets to the 12.8° AoA (IIRC) where it changes over to maintaining that. So it still behaves the same—side-stick to select where you are going and thrust levers to adjust how fast (except they need more attention on the back of the power curve).

That's not how C* works. C* controls pitch rate/Nz. In steady-state, C* cmd of 0 corresponds to steady flight path; it's not a control strategy: it's a fallout. In the back-side, no matter if it's C*, pure Nz or direct elevator, controlling flight path is unstable. It's possible that underspeed corresponds to before the backside starts, but I doubt it.

@JZYL, the reference for normal law is vertical acceleration, with pitch used for filtering at slow speed. It is indeed unstable—when the aircraft starts pitching up, the increased drag will slow it down, which will require further pitch up until it hits alpha-min. But computer does not have any problem maintaining unstable parameter; it just will (with some deviation, because it responds to the rate, not absolute value except in flare). That leaves the speed. With manual thrust you'll need to fiddle with it all the time, with auto-thrust computer has no problem with unstable parameters.

It's not desirable. Airbus had to get special permission from at least the FAA if memory serves, just to get their FBW aircraft certified with such a design. It's simply to allow for workload reduction in not having to trim the horizontal stabilizer after a pitch up input is given where the autotrim will trim the trimmable horizontal stabilizer (THS) automatically to give neutral stability. It makes life easier for the pilot. It certainly does have it's disadvantages as you pointed out where it would stall itself if airspeed bleeds off too much or too fast. I'd also like to say it makes stalling the FBW Airbus much easier while in alternate law as it'll maintain your nose up attitude and you don't have any artificial force feedback from the FBW to have to trim for.

I did not find much about the decision process airbus went through, but my layman idea about their motivation is reduced pilot workload - with pitch stability it gets easier to hold a constant altitude also in manual flight, without the need to use trimming input. flying a hold gets compareably easy - demand some roll rate to the intended bank and go back to neutral. Pitch stability will keep the plane more or less at the current altitude, only little corrections needed. I guess reducing pilot workload is always a potential selling point for new designs (whether they actually do or not)

The use of C* was dictated to AB once they made the design decision to, for almost all practical purposes, eliminate feel.  They made this decision due to their estimate that it would weigh five tonnes extra to do so.  This decision was made in the seventies, even so, that weight estimate strikes me as on the high side.  The main thing is, they would save a reasonable amount of weight by not having feel.
That then dictated, for certification purposes, a load based flight control law, due to the lack of feel.  C* blends pitch rate in as well.  This was acceptable to certifying authorities, though it did require regulatory change, as there is no longer a trim speed.  Instead, as you stated in the question, when you let go of the stick, the aircraft maintains the attitude you left it in, unless one of the protections in the flight control laws has to operate, protections which have to be there is no trim speed, as you state in the question.
There are a lot of intricate detail differences in the main AB flight control laws, with the A320 series having the most "kludges" to give it acceptable handling, such as imposing nose down trim in flare mode, so that pilots pull back to flare.
When it all works, it is fine, and it actually does a pretty good job at protecting against some serious pilot blunders too.  In that very small number of cases where it doesn't work as it should, it can be an absolute nightmare, making the pilot almost a passenger as the aircraft actively tries to kill you by such niceties as flying you into the ground.  Thankfully, actually hitting the ground hasn't happened yet, but serious injury has certainly been inflicted.  Then there are all those cases where the aircraft is operating in a degraded mode and the pilots have become so habituated to how it normally works so well that they can't cope with it when it misbehaves.  Having flight controls not indicating what the aircraft or the other set of flight controls is doing does limit pilot ability to understand what is going on and can have very bad outcomes.  The AB architecture tends to overload the visual channel, whilst removing almost all other cues as to what is going on.  Visual channels are easily saturated by task fixation, and that tiny little message letting you know that the right seat is pulling back with all their might whilst you are pushing forward to get out of the stall is super easy to miss.  I'd urge all FBW AB pilots to get into the habit of pushing the priority button anytime (presuming that company SOP allows this) they say they have the controls, so that it gets pushed when you take over in a high stress situation.  At least you will know that whatever response you are getting from the aircraft is going to be related to what you are doing.
I don't think the C* law is any way desirable on its own, CU seems much better to me.  However, by using C, AB were able to reduce weight, whilst bringing in many protections, which, despite the bad side of the scheme, have overall probably enhanced their accident record, even though it has contributed to or even caused accidents even when the system has been fully operational, through such fun things as halving roll authority on first touch when you have full roll in on a challenging crosswind landing, or disabling spoilers and reverse thrust because not all the wheels have enough weight on them, or preventing a pilot from flaring, causing a hard landing.  These are usually one off cases, as the problem in the requirements specification is revealed, so the software is revised.  Particularly with primary flight controls, I don't think the "dead stick", ignored by the computer is the way to go, rather moving the pilots inceptor, so they know what is going on, and having forces that they can overcome when something goes awry with the computer flight control.  That way, when something totally cockeyed happens, like alpha protections pointing you at the ground in the cruise, you aren't just along for the ride.  But for every bad example, there is usually a good example, where the AB way has saved the day and other systems probably wouldn't have.
So it is all about weight restrictions resulting in a very limited artificial feel system (most would say no feel), which then imposes the kinds of control law you have to use.

I'm not sure I understand why CstarU would increase weight. A220s use a version of Cstar with speed stability added on top, but it's all done through software with passive sticks.


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What do aircraft accident investigators do in between incidents?
Consider aircraft accident investigators in your average first- or second-world nation. Something like the US NTSB, the French BEA, the Canadian TSB, the Australian TSB, ... (whichever you happen to be most familiar with is fine)
Now, most of the time, aviation ticks along nicely. Aircraft take off, aircraft cruise, aircraft land. Aircraft are checked up and maintained. It's not like you are going to call in an accident investigation team for a hard landing or a broken light bulb.
Yet when something does happen (especially in a known location) that warrants an investigation, investigators are on the scene quickly, not uncommonly within hours of an incident.
Considering how long investigations can take to complete, it seems likely that multiple teams would be needed, so that one can be brought in quickly without unnecessarily disrupting any ongoing investigation. (Aircraft incidents do, unfortunately, happen more often than once every several years, especially in large countries with significant amounts of air traffic.) On the other hand, incidents happen rarely enough that it seems to me, most of the time, a large number of such investigators would basically be sitting around just waiting for something to go wrong. That doesn't seem reasonable, so...
What do these people actually do while aviation pretty much just works?

Considering how long it takes to get an official report out after the incident actually occurs, I'd say they're busy, you know, investigating... ;)

let's hope they aren't praying for work!

@Michael Or, even worse, generating work!.... Hmmmm.... .

@OscarBravo Cue second investigation team that just can't figure out why the incident rate skyrockets whenever Joe is on duty.

Also, note that of the four agencies you mentioned, only one exclusively handles aviation issues. It's possible that some staff (likely less technical) also deal with rail, sea, road etc. incidents.

What do firemen do between the fires? But seriously, investigations take so long that it's unlikely that one would ever have nothing going on.

NTSB investigators handle General Aviation incidents that you never hear about, as well as the Commercial incidents that make the nightly news.
There are new incidents every single day.
Try reading AVHerald for a sense of what happens, or searching the NTSB Aviation Database.
They have plenty of work.

If only you could monitor all the airport frequencies and count the number of times in the day someone says the word "phone number"...

Also remember NTSB isn't fixated on aviation.  They investigate train accidents, and other public transit accidents.

Do NOT read this if you're planning on flying (any time soon / ever).

@Strawberry: TBH, I was suprised that there are so few crashes and accidents, given the number of flights just an this very moment:  https://www.flightradar24.com/ . Adjusting my work commute to minimize public traffic is way more important to me; especially since I entered the world of work, I have been part of quite a large number of near-accidents which would have been deadly to many (German Autobahns, combined with too many Germans "having it under control", you know). Planes even seem safer than staircases at railstations, to me.

Look at how many of those incidents still result in passengers getting to their destination safe-n-sound, with only a minor delay.  Landing Gear problems, engine failures, bird strikes, and all manner of issues, but no one is injured or killed, and only has a minor delay.  Aviation is truly remarkable.

Nice headlines they use: aircraft ain't no lawnmower

@BillyC. They have separate departments for each type of transportation, while they may certainly help each other out I think a lot is specialized and they typically stay within each department.

@abelenky by coincidence I just read this paper which has a section on the NTSB - it seems like they themselves deserve a lot of the credit for how many of these incidents can nowadays happen without serious harm to anyone https://www.newyorkfed.org/medialibrary/media/research/epr/2016/epr_2016_gordon-gekko-effect_lo.pdf?la=en

@BillyC. that applies to the USA. Other countries have their investigation boards organised differently and often one is specialised in aviation incidents.

It's not like you are going to call in an accident investigation team for a hard landing or a broken light bulb.

For a hard landing you certainly would. They'd just send one or two investigators, but they'd still want to see the report generated by the system, interview the pilots, possibly download the FDR and CVR data. And then they'll analyse the situation and may further inquire into the training procedures and pilot pairing and a lot of things. It's not just analysis of the big accidents, but constant review of all the safety procedures that keeps the operation safe.

On the other hand, incidents happen rarely enough

Incident is any occurrence that might affect safety. Hard landing is an incident. Engine failure is an incident, as is failure of any other flight-related system like air conditioning, electric generator, anti-ice, flight control etc. Pilot incapacitation is an incident. Incorrect ATC instruction is an incident, as is incorrect execution of a correct instruction. Many things are.
All these things are reported to the investigation board. And then they decide how much they are going to investigate them. Sometimes they look at the report, conclude that the safety checks worked and there is no point in investigating further, other times they will do more or less careful review of those checks. And sometimes they will return to the reports when they notice some kind of incident is unusually common, as it likely indicates some underlying problem that should be addressed.
So they do have a lot of work even if there is no major accident.

Is "Harrison Ford getting in his plane" an incident?  : )

@GrimmTheOpiner, only when he's flying solo.

@Wossname I'm not sure I'd feel better with someone like Tom Cruise up front left. Lots of people in their field have an ugly tendency to get into trouble... :-)

And yes, they actually do investigate things like a hard landing; I just read such a report earlier today: three pages of statistics about the plane, pilot and airport, and two sentences describing the damage and blaming the pilot for a bad flare. I imagine that's what they do to keep in practice while waiting for the next airliner to go down.

@StephenSprunk, they do it to try to delay the next airliner going down as much as possible; the statistics are to notice systemic issues early, in this case probably whether the quality of recurrent training in the airline declines.

A broken light bulb absolutely can result in an accident investigation.    An indicator failing is not in itself a problem, but the crew's reaction to that failed indicator is very much something which accident investigators are interested in.  Several similar accidents around the same time as Flight 401 emphasised an endemic problem of flight crew failing to keep situational awareness and actually fly the aircraft whilst fault-finding problems.  That fed into improved training for pilots and engineers, as well as best practise for manuals.
So the assumption that aviation "just ticks along nicely" is not really true.  These days we have many fewer accidents, but part of that comes from constant scrutiny, and that constant scrutiny needs people.  And it can be quite small things which show up a bigger problem.

Do note the difference between light bulb and cockpit indicator light. A light bulb could be the indicator light for the landing gear down/locked position (that's one that you certainly would rather have working), or it could be one of the gazillions of "do not smoke" illuminated signs in the cabin of a large airliner. When writing that comment, I had in mind more the latter than the former.

So what do they do between accidents? Is this an answer to that question?

@MichaelKjörling If people start smoking because of that light not being on, it could also be a kind of incident ;-)

@VladimirF Fair point.  I've added a second paragraph for clarification.

@MichaelKjörling: Which, judging from the number I've seen burned out in all my flying, nobody seems to care much (or at all) if they burn out.

Investigators take turns being on the "go team", in which they are expected to be able to travel within short notice to investigate an incident. While the major accident investigations dominate headlines, there are many other responsibilities of investigating agencies to keep the agents busy. Examples in this post come from the NTSB's 2016 Annual Report, where they detail accomplishments.
Small Incidents
The NTSB is tasked with investigating "each accident involving civil aircraft." This includes not only commercial airliners but also general aviation. In 2016 they released 1,272 accident briefs. Although these will generally not be anywhere near the complexity of an airliner accident, it still requires gathering information, reviewing evidence, determining causes, and compiling reports. They also assist in some international investigations.
Recommendations
Investigating agencies also issue recommendations to regulators about how safety can be improved. Recommendations may arise from a single incident, or multiple incidents sharing similar factors. This may require further investigation or research in order to justify the costs of new rules. They also must review the responses provided by regulators for these actions, and determine whether they acceptably address the recommendations. In 2016, the NTSB issued 54 new recommendations, closed 48 as acceptable, and closed 7 as unacceptable.
Outreach
Investigators also take part in presentations, seminars, and forums on safety topics. They also help produce safety alerts and videos.
Training
As with any job, there is plenty of ongoing training to stay current with laws, technology, and tools that affect their jobs.
Although the NTSB investigates transportation incidents in other areas besides aviation, each type of transportation has a different office, and investigators are assigned to a certain office. The Aviation Safety office is by far the largest. While investigators may help out other offices, many skills are specialized and they generally don't work on incidents for other offices.

Knowing a few members of aviation safety boards myself, most of them do have a 'normal' job besides their work for the safety board. Board members who might play an important role at accident investigation do have a suitcase packed in case they need to hurry to an accident location. But besides that, when nothing happens, they just live their normal lives.

"they just live their normal lives", well obviously, don't well all? The question asks what work they do in the time between crash investigations. -1

@nobism The answer specifies that: "most of them do have a 'normal' job besides their work for the safety board."

Are you talking about the actual board members (of which there are only 5 for the NTSB), or the accident investigators working for the agency managed by board?

What kind of "normal" job? Working in McDonalds? Or something else aviation-related?

@nobism Kinda lame to write "-1" when you don't even have the reputation to downvote. But, hey, it's a good job you don't, since your downvote is completely unfounded.

@DavidRicherby It's not uncommon to indicate "-1" in a comment even if one doesn't downvote. Sometimes that can be because the answer is not good, but it's already low enough compared to other answers that it's not a problem, sometimes it's because you don't have the required rep yet. Nothing lame about that.

@DavidRicherby I disagree it’s unfounded, apparently so do others.

I can only speak to traffic investigations - but am guessing it is similar.  An investigation requires a variety of skill sets. For a large traffic investigation, there would be agency police officers, detectives, traffic engineers and surveyors that would make up the investigation team.  Each of these responders do have a regular work load (engineering, surveying, law enforcement in the agency) when there is not an accident.  However, they also attend training and exercises as needed.

An accident investigation team is usually made up of representatives of multiple organizations: the government is one, but there are also representatives from the airframer and any suppliers of parts that have been determined to be likely at least in part responsible for the accident.
I work for a supplier of a major aircraft part. The way my company does it is that we have a small accident investigation team that is ready to go when needed. They get special training in how to respond. But their full-time jobs are not accident investigation. They are engineers within the company doing a variety of jobs, including other safety assurance processes (of which we have a whole department), validation of new engines, design, reliability, etc.
I will also note that we are doing constant low-level investigations of events, such as part failures, fault messages, delays and cancellations. We have a robust mechanism for reporting and investigating safety concerns, and on top of that we are constantly working to improve reliability (minimize inconvenience to our customers, even if faults are not a safety concern).

authors: Vladimir F Героям слава


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First actual flight lesson, what to keep in mind?
With any luck, I'll soon be going into the air for my first actual flight lesson.
Short of the obvious (get a good night's sleep before; eat appropriately; try to not stress out; etc.), what should one keep in mind in anticipation of such a milestone in one's pilot training?

Have fun, don't get discouraged if you get motion sick. In the grand scheme of things in your training it's not that big of a deal (like first solo, or first cross country solo), so don't make it one. The first flight is more about getting to know you, the instructor, and the airplane than it is about learning to fly.

Don't overthink it ;-)

Close voters:  I disagree that answers to this question would be opinion based.  Any CFI can and should be able to give an objective answer, and I suspect that most of them will be similar to mine.

I wore winter boots to my last flying lesson. My CFI said that was a big mistake since it made it hard to feel the rudder pedals under my feet.

Bring a camera. That's about it.
Unless you're training part 142 (you probably aren't) and were given homework (you probably weren't) your first flight is where you get to see what it's like to be in a small airplane, feel the controls, and get a sense of practices and procedures.
Nobody expects you to be good at anything at this point.

Instructor responsibilities during the first lesson:

Ensure the safety of the flight
Introduce you to the airplane and to basic flight operations, including straight and level, basic turns, climbs, and descents.
Answer your questions
Get your contact information and learn when and how you would like to be contacted.

Student responsibilities during the first lesson:

Be a sponge: look, listen, absorb.  You're not going to understand everything the first time, but start getting the general feel.
Ask good questions. Your instructor will be able to answer them, or if they're not relevant, she'll defer them to a later time when you have more foundational knowledge to build an answer on.
Ask stupid questions.  You're on day one.  How are you supposed to know a good question from a stupid question? If you're afraid to ask the stupid ones you'll miss out on asking the good ones.  Your instructor doesn't care about stupid questions. She'll either defer them or respectfully let you know that they're not relevant. If she's an excellent instructor she'll also file away the fact that you asked as a point of possible misunderstanding to touch on later when you have a better base of knowledge.
Get your instructor's contact information and learn when and how she would like you to contact her.
Take a bunch of pictures. It's your first flight lesson!

Only one of these requires advance preparation. Got a camera? Good. Go have fun.

"Does this headset make my ears look big?" :-)

Forget the aviator sunglasses and leather bomber jacket.  However, you might want to dress in layers for the weather. It can be windy and cold on the ramp.
Have writing stuff (like a small or mid-sized notebook and pencil) handy to take notes.  But don't stress on the notes, rather try to absorb what you can from your instructor.
You may wish to eat light prior to the flight, as that my minimize the likelihood of any motion sickness, which many initial primary students may experience from time to time.
Be ready to absorb material, and understand that at the first lesson you don't have to remember everything in detail.
Here's some of the stuff I cover on the first flight:

aircraft documents, POH, checklist locations
Doors, latches, compartments and pockets
seat belts, windows and airvents
overview on controls and control surfaces
overview on electrical, vacuum and pitot/static systems and instruments
preflight and checking engine oil, belts, etc.
starting engine (instructor runs controls for this flight)
radio communications (usually done by instructor for this flight)
taxi aircraft, started by instructor, then done by student
takeoff demo with student following through on controls
trim and control forces
climb (done by student)
cruise power settings (demo first, then student does)
turns (demo first, then done by student)
some configuration changes, like flap extension (optional)
return to airport (instructor doing most or all of communications)
approach and landing (instructor takes over at some point)
checklist usage
postlanding taxi by student to ramp, instructor assisting
postflight procedures, and securing aircraft
debriefing
identifying study materials, laying out the next couple of lessons, etc.

Expect that you will be operating the flight controls 50 to 90 percent of the time.
I book primary initial flights for 2 hours, and later flights for 90 minutes. Times differ depending upon school, FBO, private or club aircraft, and servicing details.
You are essentially hiring a tutor, and if you think the chemistry isn't right, you can always switch to a different instructor.  Instructors have different styles and some flex their styles to their students needs better than others.  So if the chemistry doesn't seem right, just go with it for a flight or two, and see how it works out.


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When were civilian aircraft first directed between aerodromes by air traffic control?
I feel fairly certain that when the Wright brothers flew, they did not need to contact air traffic control for clearances.
These days, it isn't uncommon for the entirety of a flight to be under ATC control, from before leaving the departure gate to after landing. Even flights in uncontrolled airspace can make use of services provided by ATC.
Ignoring early departure and late approach and landing, and instead focusing on the en-route or cruise part of flight, when was the first time civilian aircraft were directed or guided from one aerodrome to another by air traffic control (or perhaps rather, what would later evolve into modern ATC; I doubt it was called "air traffic control" at the time) in a manner similar to today's? Where in the world did this take place?

In the 1920's U. S. Airmail used a slightly older method

Probably about the same time we called them aerodromes.

I think you need to be clearer about the distinction between "control" and "make use of services".  As a GA pilot flying VFR, I can use services such as flight following, traffic advisories, even flight plans, but once I'm away from a towered airport (or other controlled airspace), those are voluntary, not controlling.

In 1920, Croydon Airport, London was the first airport in the world to introduce air traffic control.
In the United States, air traffic control developed three divisions. The first of air mail radio station was created in 1922 after World War I when the U.S. Post Office began using techniques developed by the Army to direct and track the movements of reconnaissance aircraft.
In 1930, the first radio-equipped control tower in the United States began operating at the Cleveland Municipal Airport.
(Source)

This answer would be great with some references.

@Jamiec Thanks for the advice. I added a link.

This is interesting, but it doesn't seem to answer the question about en-route ATC (as opposed to Ground/Tower/Approach/Departure at a particular field.)


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Stick in center console, how to easily write down clearances and other similar information?
I write with my right hand. I can make sort of intelligible scrawls with my left hand, but that is much slower for me.
The airplane I'm training in is a single-engine prop plane with the control stick (not yoke) in the center console, between the seats, rather than directly in front of the pilot. (For those curious, it's an Ikarus C42B. Here and here are some photos of what the interior looks like; your favorite search engine will show you many more, including all kinds of variations to the panel layout.)
Sitting in the left-hand seat, this means that my right hand is operating the control stick, which also has the PTT and trim controls plus the main brake handle. (I typically keep my left hand on the throttle lever, which in this aircraft is between the legs of each pilot. Yes, this means there are two throttle controls and one control stick.)
This combination presents an obvious obstacle when trying to write down things like clearances, as I'll have to either:

use my left hand to write, resulting in difficult-to-read scribbles (certainly not ideal), or
use my right hand to write, requiring reaching over with my left hand to the control stick (awkward), or
use my right hand to write, letting go of the control stick and trusting that the aircraft will fly reasonably straight and level (requires much trust in the aircraft)

Any practical tips on how to handle a situation like this? (Surely I can't be the only person in this situation.)
The aircraft is equipped only for VFR; no autopilot of any kind, no IFR instruments, etc. So I'm only interested in VFR during VMC, but with the possibility of some turbulence and possibly in controlled airspace. (If I somehow manage to end up in IMC, ATC will just have to put up with me until I'm back in VMC...)
Since there seems to be some confusion, here are some examples of the kind of information I'd like to be able to write down:

taxi instructions
landing instructions, including e.g. runway in use
altimeter settings (e.g. QNH value, transition level or transition altitude)
frequencies
reporting positions and altitudes ("report 3,000 feet climbing", "report BAZ")
instructions for where to enter or exit controlled airspace, or where to transition from one controlled airspace to another ("cleared entry via FOO, 2,500 feet or below")
transponder codes, especially when assigned a code different from the local default VFR code (1200 in the US, 7000 in Europe, ...)
cleared altitude or flight level

There's probably much more that I'm just not thinking of right now. While some of this is in a relatively relaxed environment on the ground, some of it needs to be handled in the air.
One of these days I plan on trying to simply let go of the stick for a few moments (after trimming for level flight) to see how well the plane actually maintains straight and level flight on its own with at most rudder inputs, but other than that, I'm having trouble coming up with ways of actually handling this situation. How do other pilots do it?

Of course, if anyone has ideas for appropriate tags to add to this question, by all means feel free.

I use to fly this plane, central stick and single, central throttle. One gets used... This is it: https://imgur.com/2Brb6dJ  When I have to write something, I hold the stick with my left hand, and write with my right hand on a pad on the right seat. The throttle stays where it is, because it's a button-lock vernier...

@xxavier The throttle on this plane doesn't need constant hand-holding either, I just find it's as convenient a spot as any for my left hand when it's not needed for anything else. It's no problem to let go of the throttle to adjust other controls, including things like magnetos during the engine run-up (at which point I'll be holding the brake, which is also on the control stick, because the parking brake isn't powerful enough to prevent movement when the engine is at full whallop).

use my right hand to write, letting go of the control stick and trusting that the aircraft will fly reasonably straight and level  .... a well trimmed aircraft in clear air will fly straight and level. No trust is required. In less than perfect conditions, your first priority is to fly the aircraft not write things down.

One technique many airline pilots use is to enter letters and numbers on the FMC keypad to use as a reminder for complicated taxi instructions.
“taxi via Hotel, cross 15L, right turn Bravo, hold short Alpha One” could be entered on the keypad as: HX15LB/A1 or possibly H X15L B/A1
There really is no requirement to write down this type of instruction, or any VFR clearance. It is just a reminder and makes for good airmanship.
Many FOs in the right seat seem to use their left hand when entering data in the FMC as it can feel awkward to reach over and punch buttons with your right hand.
In your case you might be able to use an iPad or some other type of electronic device on a knee pad to punch in some “shorthand” with your left hand to help you remember what ATC says.

Even using my right hand I've developed a similar short hand writing style that helps when ATC is rattling instructions off as quick as they can talk.

I finally got a chance to try what I wanted to; obviously, after first discussing it with the instructor on the ground, before we got into the plane.
Having first trimmed for level flight at a safe altitude, I simply let go of the stick altogether. The plane was plenty stable enough that we could probably have flown for a good amount of time like that, with at most small rudder inputs to stay on course.
Obviously, it's more involved in turbulent air (this was on a rather calm day) or while actively maneuvering. This does however give me one preferable option to use when conditions allow, and saves the more complicated variants for those times when they are needed.
Next step at some point is probably to try it with real-life ATC comms, but that's for later.